1. The Field of the Invention
The present invention relates generally to penetration and dissolution devices. More particularly, it concerns a hollow amplifying tip for amplifying the velocity of ultrasonic energy produced by an ultrasonic transducer and delivering the energy to a subject to be penetrated or modified.
2. The Background Art
Modern surgery involves the insertion of various surgical tools into a patient, which requires incisions to be made in the patient. It is known in medical technology to create an artificial access to body cavities and organs within the patient which do not posses any natural communicating passage to the patient's exterior. Cannulation instruments known as trocars have been used for this purpose.
For example, in endoscopic surgery a sharp-pointed trocar removably surrounded by a sleeve is used to penetrate the peritoneum. The trocar pierces the body tissue and widens the opening to the diameter of the sleeve. The sleeve is pushed into the opening and the trocar is removed from the sleeve. The sleeve remains lodged in the opening to serve as a passageway through which endoscopes and other surgical tools can be inserted and removed.
The insertion of the trocar, even with the advantageous selection of an injection site, involves the risks of inadvertently damaging delicate internal organs and blood vessels in the peritoneum and surrounding fatty tissues. There is also the risk after penetration that organs and blood vessels within the abdominal cavity can be damaged by further movement of the trocar.
Attempts have been made in the prior art to solve these problems. For example, U.S. Pat. No. 5,271,380 (issued Dec. 21, 1993 to Riek et al.) discloses a penetration instrument which includes optical fibers used to illuminate the organs and blood vessels to the view of the surgeon. This device attempts to provide observation of the area lying directly in front of the sharp-pointed trocar, to avoid inadvertent damage to the organs and blood vessels. In this application as well, however, piercing the peritoneum with a sharp-pointed object remains the central method of penetration, and thus the risk of damage during insertion of the trocar remains.